An overflow box filter is formed of plastic. It includes connections for external filter supply and drain tie-in, window for viewing inside, sponge filter, carbon filter, manual or electronic priming system, top surface skimming slots, over the wall pipe chase, water top off or feeding port, manual or electronic feeding system, powerhead/(s), system control interface, probes and sensors. The unit hangs on any tank rim, external panel or side wall and may be sized to match any system load requirement. Use includes manual or automatic priming, the transfer of water from one tank to another, internal supply and return flow, and the ability to provide food manually or automatically from a submerged food release port.